Bootstrap 3 no longer supports tab directions

[jonnypolite]

The css classes tabs-left, tabs-right, and tabs-below no longer exist in Bootstrap 3. This makes the 'direction' attribute in the tabset worthless, unfortunately.

Figured I'd open an issue so that the direction code can be removed.

[pkozlowski-opensource]

Yes, we've noticed this. Going to keep this issue open so we can remove the dead code (actually the direction thing was causing other sort of problems so it is good to remove this code anyway).

[chrisirhc]

Related to #1362

[bekos]

@jonnypolite Directions has already been removed by this commit c9acebb.